Yellowstone was designated as the first national park in the world in 1872 and also became one of the first biosphere reserves about 100 years later. The area is part of the most seismically active region of the Rocky Mountains and lies on a volcanic ‘hot spot’. Thus, Yellowstone is well known for its hydrothermal features such as geysers, hot springs and mud pots. It contains more geysers than all the rest of the world, along with 200-250 active geysers and some 10,000 thermal features.Approximately 80% of the park is forested with lodgepole pine (Pinus contorta) as the predominant tree species. However, great differences in altitude produce a range of plant communities, from semi-arid steppe to alpine tundra. Yellowstone is equally known for its wildlife, namely elk (Cervus elaphus), mule deer (Odocoileus hemionus), bison (Bison bison), moose (Alces alces), bighorn sheep (Ovis canadensis), pronghorn (Antilocapra americana), and white-tailed deer (Odocoileus virginianus) and, as carnivore, the grizzly bear (Ursus arctos).However, the nature of Yellowstone is not untouched any more. Mining operations adjacent to the park might compromise its values by threatening the watershed ecology of the Yellowstone River. Other issues include sewage leakage and waste contamination, road construction, year-round visitor pressures, and the introduction of non-native lake trout which are competing with the endemic Yellowstone cut-throat trout. Threats to the bison population are apparent in proposals to slaughter large numbers of them as a control measure to eradicate brucellosis bacteria in the herds, which is perceived as a threat to cattle. Yellowstone provides an excellent area for research with studies on large mammals, fisheries, vegetation, fire ecology and geology.